Former US Open champion Medvedev was pushed hard in the previous round by Lorenzo Sonego, saving nine set points before winning the first set, but had an easier time of it against Serbian Kecmanovic, the world number 29.

"I think it was a great match. Miomir is a tough opponent, a high-ranked player, so there are no easy guys left in Adelaide," Medvedev said.

"I'm not sure there were (any easy opponents) from the first round, so I'm happy to be through, happy with my level."

Up next for world number seven Medvedev is a meeting with compatriot and eighth seed Karen Khachanov, who beat Briton Jack Draper 6-4 6-2.

"I was expecting a tough battle against Jack because we had a good battle at the U.S. Open which unfortunately finished not in a way I wanted," said Khachanov, who prevailed when Draper retired with a hamstring injury at Flushing Meadows last year.

"He's on a good run, he is a young, rising player. From the beginning to the end I played a solid match ... with all the components of my game, I was pretty satisfied today."

Also advancing to the quarter-finals of the ATP 250 tournament was Japan's Yoshihito Nishioka, who followed up his stunning win over Paris Masters champion Holger Rune with a 6-4 6-3 victory over American Mackenzie McDonald.

The Australian Open runs from January 16-29 at Melbourne Park.